1. Field of the Invention
The invention relates to the use of a cylindrical test body with one or more spherical cavities for testing the function and defect recognition quality of systems for the visual or automatic recognition of defects in castings and a method for the manufacture thereof.
2. Description of the Related Art
Modern systems for the automatic recognition of defects in castings, so-called ADR systems (automatic defect recognition) must be able to reliably detect ever smaller defects. The smallest attenuations and interferences in the signal chain can lead to defects no longer being reliably detected. At the same time the presently used methods for enabling conclusions to be drawn concerning defects and defect sizes by means of 2D/3D filming, require an adaptation in accordance with practice, so that in the forefront of the interpretation of an ADR system a valid statement can be made concerning the possible recognition quality.
In conventionally used methods, the function of the system is tested with wire penetrameters, e.g. DIN 54109 or platinum double wire webs (standard EN 13068-3), or by means of inspection parts provided with clearly defined bores; or perforated plates applied to inspection parts, e.g. ASTM E-1025.
All these testing and inspection possibilities are not really in accordance with practice. The first unit only tests the resolution and cannot be used for detection purposes. The second unit is scarcely reproducible, because the drilling depths are individually set, the drilled hole is conical and as a result of the cylindrical shape of the hole or bore, the transmission direction has a considerable influence on recognition. The third possibility, using a penetrameter, suffers from the same problem that the detectable size of the objects is dependent to a significant extent on the transmission direction as a result of the cylindrical geometry. In addition, the sharp edges of the bores provide contrasts not in accordance with 3D defect practice. The first and third methods also suffer from the fact that the test bodies cannot be fixed to the part to be inspected in the installation and then allow an automatic installation calibration. Therefore the problem of the invention is to improve the testing and inspection possibilities for the operation and defect recognition quality of ADR systems, whilst providing an economic method for the manufacture of the test bodies used for this purpose.
Surprisingly this problem is solved by the use of a cylindrical test body with a spherical cavity for testing the function and defect recognition quality of systems for the automatic recognition of defects in castings and fixed on or in the casting to be tested.
The invention creates test objects or bodies, which better approximate the shape of natural defects and which can be manufactured easily and inexpensively in a reproducible manner. These test bodies contain one or more spherical cavities optionally of different sizes and positions. Thus, the invention makes it possible to obviate the use of wire penetrameters, defined conical bores and perforated plates.
The method of the invention for the manufacture of said cylindrical test body offers the three following alternatives:
1) a. Punching circular holes, whose diameter approximates in optimum manner the shape of a ball, in the center of a plurality of foil layers, which are made from the material of a casting to be tested. b. Superimposing the plurality of foil layers with the punched holes and adjacent to the foil layers with the smallest holes are superimposed foil layers without a hole. c. Pressing or bonding together the superimposed plurality of foil layers. or
2) a. Provision of two cylindrical test body pieces with the same diameter. b. Drilling a hemispherical recess in one end face of each cylindrical test body piece. c. Assembly by means of bonding of the test body pieces at the end faces thereof. or
3) a. provision of two cylindrical test body pieces with the same diameter. b. Provision of a circular recess in one test body piece and a corresponding circular insert in facing manner on the other test body piece and drilling a semicircular recess in facing sides of the test body piece or circular insert, and c. Pressing the circular insert into the circular recess.
The invention provides a cylindrical test body comprising one or more spherical cavities for testing the function and defect recognition quality of systems for the automatic recognition of defects in castings fixed on or in the casting to be tested.
The invention also provides a method for the manufacture of a cylindrical test body with one or more spherical cavities comprising I, II or III:
I. a) punching circular holes, whose diameter approximates in optimum manner the shape of a ball, in the center of a plurality of foil layers, which are made from the material of a casting to be tested, b) superimposing of the plurality of foil layers with the punched holes and adjacent to the foil layers with the smallest holes are superimposed foil layers without a hole, c) pressing or bonding together the superimposed plurality of foil layers;
II. a) provision of two cylindrical test body pieces with the same diameter, b) drilling a hemispherical recess in one end face of each cylindrical test body piece, c) assembly by means of bonding of the test body pieces at the end faces thereof;
III. a) provision of two cylindrical test body pieces with the same diameter. b) provision of a circular recess in one test body piece and a corresponding circular insert in facing manner on the other test body piece and drilling a semicircular recess in facing sides of the test body piece or circular insert, and c) pressing the circular insert into the circular recess.
The invention further provides cylindrical test body for testing the function and quality of a defect recognition system, which cylindrical test body is formed by the steps of I, II, or III:
I. a) providing a plurality of circular foil layers, which foil layers comprise a material of a casting to be tested; b) forming a circular hole in some of the foil layers, whereby the circular holes are sufficiently sized and aligned such that, upon superimposing the plurality of foil layers, the circular holes are capable of defining a central spherical cavity within the superimposed plurality of foil layers; c) superimposing the plurality of foil layers such that the circular holes define a central spherical cavity within the superimposed plurality of foil layers, and such that those foil layers with the smallest holes are superimposed against foil layers without holes, and d) attaching the superimposed plurality of foil layers to form a cylindrical test body having a central spherical cavity;
II. a) providing first and second cylindrical test body pieces of substantially the same diameter, wherein each test body piece has an end face which faces the other test body piece; b) forming a hemispherical recess within in one end face of each cylindrical test body piece, and c) attaching the end face of the first test body piece to the end face of the second test body piece to thereby form a cylindrical test body, and wherein the hemispherical recesses are sufficiently aligned to thereby define a central spherical cavity within the cylindrical test body;
III. a) providing first and second test body pieces having a height H, thickness T, and diameter Dm, and each test body piece further comprising a hemispherical recess having a diameter Dz; b) providing a spherical insert having substantially the same diameter as the hemispherical recesses; c) placing the spherical insert within the hemispherical recess of the first test body piece such that a first half of the spherical insert is within the hemispherical recess and a second half of the spherical insert faces the second test body piece; and d) placing the second test body piece onto the second half of the spherical insert to thereby attach the first and second test body pieces, thus forming a cylindrical test body with a central spherical insert.
The invention still further provides a process for testing the function and quality of a defect recognition system, which process comprises the steps of: i) providing a cylindrical test body for testing the function and quality of a defect recognition system, which cylindrical test body is formed by the steps of I, II, or III:
I. a) providing a plurality of circular foil layers, which foil layers comprise a material of a casting to be tested; b) forming a circular hole in some of the foil layers, whereby the circular holes are sufficiently sized and aligned such that, upon superimposing the plurality of foil layers, the circular holes are capable of defining a central spherical cavity within the superimposed plurality of foil layers; c) superimposing the plurality of foil layers such that the circular holes define a central spherical cavity within the superimposed plurality of foil layers, and such that those foil layers with the smallest holes are superimposed against foil layers without holes, and d) attaching the superimposed plurality of foil layers to form a cylindrical test body having a central spherical cavity;
II. a) providing first and second cylindrical test body pieces of substantially the same diameter, wherein each test body piece has an end face which faces the other test body piece; b) forming a hemispherical recess within in one end face of each cylindrical test body piece, and c) attaching the end face of the first test body piece to the end face of the second test body piece to thereby form a cylindrical test body, and wherein the hemispherical recesses are sufficiently aligned to thereby define a central spherical cavity within the cylindrical test body;
III. a) providing first and second test body pieces, each having a height H, thickness T, and diameter Dm, and each test body piece further comprising a hemispherical recess having a diameter Dz, such that the first and second test body pieces are capable of forming a central spherical cavity upon attaching the test body pieces together; b) providing a spherical insert having substantially the same diameter as the hemispherical recesses; c) placing the spherical insert within the hemispherical recess of the first test body piece such that a first half of the spherical insert is within the hemispherical recess and a second half of the spherical insert faces the second test body piece; and d) placing the second test body piece onto the second half of the spherical insert to thereby attach the first and second test body pieces, thus forming a cylindrical test body having a central spherical cavity which contains the spherical insert; ii) providing an automatic defect recognition system comprising a defect detector; iii) measuring the spherical cavity of the cylindrical test body in three dimensions with the defect detector, to test the image quality of the defect detector and to calibrate the defect detector.